Multi-step system and method for curing a dielectric film

ABSTRACT

A multi-step system and method for curing a dielectric film in which the system includes a drying system configured to reduce the amount of contaminants, such as moisture, in the dielectric film. The system further includes a curing system coupled to the drying system, and configured to treat the dielectric film with ultraviolet (UV) radiation and infrared (IR) radiation in order to cure the dielectric film.

CROSS-REFERENCE TO RELATED CASE

This application is a continuation of and claims the benefit of priorityfrom U.S. application Ser. No. 12/605,863, filed on Oct. 26, 2009, whichis a divisional of U.S. application Ser. No. 11/269,581, filed Nov. 11,2005 (now U.S. Pat. No. 7,622,378, issued Nov. 29, 2009). The entirecontents of these applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multi-step system and method fortreating a dielectric film and, more particularly, to an in-situ,multi-step system and method for drying and curing a dielectric film.

2. Description of Related Art

As is known to those in the semiconductor art, interconnect delay is amajor limiting factor in the drive to improve the speed and performanceof integrated circuits (IC). One way to minimize interconnect delay isto reduce interconnect capacitance by using low dielectric constant(low-k) materials as the insulating dielectric for metal wires in the ICdevices. Thus, in recent years, low-k materials have been developed toreplace relatively high dielectric constant insulating materials, suchas silicon dioxide. In particular, low-k films are being utilized forinter-level and intra-level dielectric layers between metal wires insemiconductor devices. Additionally, in order to further reduce thedielectric constant of insulating materials, material films are formedwith pores, i.e., porous low-k dielectric films. Such low-k films can bedeposited by a spin-on dielectric (SOD) method similar to theapplication of photo-resist, or by chemical vapor deposition (CVD).Thus, the use of low-k photo-resist, or by chemical vapor deposition(CVD). Thus, the use of low-k materials is readily adaptable to existingsemiconductor manufacturing processes.

Low-k materials are less robust than more traditional silicon dioxide,and the mechanical strength deteriorates further with the introductionof porosity. The porous low-k films can easily be damaged during plasmaprocessing, thereby making desirable a mechanical strengthening process.It has been understood that enhancement of the material strength ofporous low-k dielectrics is essential for their successful integration.Aimed at mechanical strengthening, alternative curing techniques arebeing explored to make porous low-k films more robust and suitable forintegration.

The curing of a polymer includes a process whereby a thin film depositedfor example using spin-on or vapor deposition (such as chemical vapordeposition CVD) techniques, is treated in order to cause cross-linkingwithin the film. During the curing process, free radical polymerizationis understood to be the primary route for cross-linking. As polymerchains cross-link, mechanical properties, such as for example theYoung's modulus, the film hardness, the fracture toughness and theinterfacial adhesion, are improved, thereby improving the fabricationrobustness of the low-k film.

As there are various strategies to forming porous dielectric films withultra low dielectric constant, the objectives of post-depositiontreatments (curing) may vary from film to film, including for examplethe removal of moisture, the removal of solvents, the burn-out ofporogens used to form the pores in the porous dielectric film, theimprovement of the mechanical properties for such films, and so on.

Low dielectric constant (low k) materials are conventionally thermallycured at a temperature in the range of 300° C. to 400° C. for CVD films.For instance, furnace curing has been sufficient in producing strong,dense low-k films with a dielectric constant greater than approximately2.5. However, when processing porous dielectric films (such as ultralow-k films) with a high level of porosity, the degree of cross-linkingachievable with thermal treatment (or thermal curing) is no longersufficient to produce films of adequate strength for a robustinterconnect structure.

During thermal curing, it has been noticed that the appropriate amountof energy is delivered to the film without damaging the dielectric film.Within the temperature range of interest, however, only a small amountof free radicals can be generated. Due to the thermal energy lost in thecoupling of heat to the substrate and the heat loss in the ambientenvironment, only a small amount of thermal energy can actually beabsorbed in the low-k films to be cured. Therefore, high temperaturesand long curing times are required for typical low-k furnace curing. Buteven with a high thermal budget, the lack of initiator generation in thethermal curing and the presence of a large amount of methyl terminationin the as-deposited low-k film can make it very difficult to achieve thedesired degree of cross-linking.

SUMMARY OF THE INVENTION

One aspect of the present invention permits reduction or elimination ofany of the above-described problems or other problems in the prior artrelating to processing dielectric films.

Another aspect of the present invention permits treatment of adielectric film in order to cure the dielectric film.

Yet another aspect of the present invention permits treatment of adielectric film by performing an in-situ, multi-step drying and curingprocess using multiple process modules coupled to one another.

Any of these and/or other aspects may be provided by a processing systemfor treating a dielectric film in accordance with the present invention.In one embodiment, the processing system for treating a dielectric filmon a substrate includes a drying system configured to perform a dryingprocess to reduce the amount of contaminants in or on the dielectricfilm and a curing system coupled to the drying system and configured toperform a curing process. The curing system includes: an ultraviolet(UV) radiation source configured to expose the dielectric film to UVradiation, and an infrared (IR) radiation source configured to exposethe dielectric film to IR radiation. The system includes a transfersystem coupled to the drying system and the curing system. The transfersystem is configured to exchange the substrate between the drying systemand the curing system under vacuum conditions.

In another embodiment, a method and computer readable medium fortreating a dielectric film on a substrate includes: disposing thesubstrate in a drying system, drying the dielectric film according to adrying process in order to remove or partially remove contaminants on orin the dielectric film, transferring the substrate from the dryingsystem to a curing system while maintaining vacuum conditions during thetransfer, and curing the dielectric film by, exposing the dielectricfilm to UV radiation and exposing the dielectric film to IR radiation.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A through 1C are schematic representations of a transfer systemfor a drying system and a curing system according to an embodiment ofthe present invention;

FIG. 2 is a schematic cross-sectional view of a drying system accordingto another embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a curing system accordingto another embodiment of the present invention; and

FIG. 4 is a flow chart of a method of treating a dielectric filmaccording to yet another embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following description, in order to facilitate a thoroughunderstanding of the invention and for purposes of explanation and notlimitation, specific details are set forth, such as a particulargeometry of the processing system and descriptions of variouscomponents. However, it should be understood that the invention may bepracticed in other embodiments that depart from these specific details.

The inventors recognized that alternative curing methods address some ofthe deficiencies of thermal curing. For instance, alternative curingmethods are more efficient in energy transfer, as compared to thermalcuring processes, and the higher energy levels found in the form ofenergetic particles, such as accelerated electrons, ions, or neutrals,or in the form of energetic photons, can easily excite electrons in alow-k film, thus efficiently breaking chemical bonds and dissociatingside groups. These alternative curing methods facilitate the generationof cross-linking initiators (free radicals) and can improve the energytransfer required in actual cross-linking. As a result, the degree ofcross-linking can be increased at a reduced thermal budget.

Additionally, the inventors have realized that, as film strength becomesa greater issue for the integration of ultra low-k (ULK) dielectricfilms (dielectric constant less than approximately 2.5), alternativecuring methods can improve the mechanical properties of such films. Forexample, electron beam (EB), ultraviolet (UV) radiation, infrared (IR)radiation and microwave (MW) radiation may be used to cure ULK films inorder to improve mechanical strength, while not sacrificing thedielectric property and film hydrophobicity.

However, although EB, UV, IR and MW curing all have their own benefits,these techniques also have limitations. High energy curing sources suchas EB and UV can provide high energy levels to generate more than enoughfree radicals for cross-linking, which leads to much improved mechanicalproperties under complementary substrate heating. On the other hand,electrons and UV photons can cause indiscriminate dissociation ofchemical bonds, which may adversely degrade the desired physical andelectrical properties of the film, such as loss of hydrophobicity,increased residual film stress, collapse of pore structure, filmdensification and increased dielectric constant. Furthermore, low energycuring sources, such as IR and MW curing, can provide significantimprovements mostly in the heat transfer efficiency, but in the meantimehave side effects, such as for example skin layer or surfacedensification (IR), and arcing or transistor damage (MW).

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1Ashows a processing system 1 for treating a dielectric film on asubstrate, according to one embodiment of the present invention. Theprocessing system 1 includes a drying system 10, and a curing system 20coupled to the drying system 10. For example, the drying system 10 canbe configured to remove, or reduce to sufficient levels, one or morecontaminants in the dielectric film, including, for example, moisture,solvent, porogen, or any other contaminant that may interfere with acuring process performed in the curing system 20.

For example, a sufficient reduction of a specific contaminant presentwithin the dielectric film, from prior to the drying process tofollowing the drying process, can include a reduction of approximately10% to approximately 100% of the specific contaminant. The level ofcontaminant reduction may be measured using Fourier transform infrared(FTIR) spectroscopy, or mass spectroscopy. Alternatively, for example, asufficient reduction of a specific contaminant present within thedielectric film can range from approximately 50% to approximately 100%.Alternatively, for example, a sufficient reduction of a specificcontaminant present within the dielectric film can range fromapproximately 80% to approximately 100%.

Referring still to FIG. 1A, the curing system 20 can be configured tocure the dielectric film by causing or partially causing cross-linkingwithin the dielectric film in order to, for example, improve themechanical properties of the dielectric film. The curing system 20 caninclude two or more radiation sources configured to expose the substratehaving the dielectric film to electro-magnetic (EM) radiation atmultiple EM wavelengths. For example, the two or more radiation sourcescan include an infrared (IR) radiation source and an ultraviolet (UV)radiation source. The exposure of the substrate to UV radiation and IRradiation can be performed simultaneously, sequentially, or over-lappingone another. During sequential exposure, the exposure of the substrateto UV radiation can, for instance, precede the exposure of the substrateto IR radiation or vice versa.

For example, the IR radiation can include an IR wave-band source rangingfrom approximately 1 micron to approximately 25 microns and, desirably,ranging from approximately 8 microns to approximately 14 microns.Additionally, for example, the UV radiation can include a UV wave-bandsource producing radiation ranging from approximately 100 nanometers(nm) to approximately 600 nm and, desirably, ranging from approximately200 nm to approximately 400 nm.

The inventors have recognized that the energy level (hν) and the ratethat energy is delivered to the dielectric film (q′) varies duringdifferent stages of the curing process. The curing process can includemechanisms for generation of cross-link initiators, burn-out ofporogens, decomposition of porogens, film cross-linking, and optionallycross-link initiator diffusion. Each mechanism may require a differentenergy level and rate at which energy is delivered to the dielectricfilm. For instance, during the curing of the matrix material, cross-linkinitiators may be generated using photon and phonon induced bonddissociation within the matrix material. Bond dissociation can requireenergy levels having a wavelength less than or equal to approximately300 to 400 nm. Additionally, for instance, porogen burn-out may befacilitated with photon absorption by the photosensitizer. Porogenburn-out may require UV wavelengths, such as wavelengths less than orequal to approximately 300 to 400 nm. Further yet, for instance,cross-linking can be facilitated by thermal energy sufficient for bondformation and reorganization. Bond formation and reorganization mayrequire energy levels having a wavelength of approximately 9 micronswhich, for example, corresponds to the main absorbance peak insiloxane-based organosilicate low-k materials.

The substrate, to be treated, may be a semiconductor, a metallicconductor, or any other substrate to which the dielectric film is to beformed upon. The dielectric film can have a dielectric constant value(before drying and/or curing, or after drying and/or curing, or both)less than the dielectric constant of SiO₂, which is approximately 4(e.g., the dielectric constant for thermal silicon dioxide can rangefrom 3.8 to 3.9). In various embodiments of the invention, thedielectric film may have a dielectric constant (before drying and/orcuring, or after drying and/or curing, or both) of less than 3.0, adielectric constant of less than 2.5, or a dielectric constant rangingfrom 1.6 to 2.7. The dielectric film may be described as a low-k film oran ultra low-k film. The dielectric film may, for instance, include adual phase porous low-k film which may have a higher dielectric constantprior to porogen burn-out than following porogen burn-out. Additionally,the dielectric film may have moisture and/or other contaminants whichcause the dielectric constant to be higher prior to drying and/or curingthan following drying and/or curing.

The dielectric film can be formed using chemical vapor deposition (CVD)techniques, or spin-on dielectric (SOD) techniques such as those offeredin the Clean Track ACT 8 SOD and ACT 12 SOD coating systems commerciallyavailable from Tokyo Electron Limited (TEL). The Clean Track ACT 8 (200mm) and ACT 12 (300 mm) coating systems provide coat, bake, and curetools for SOD materials. The track system can be configured forprocessing substrate sizes of 100 mm, 200 mm, 300 mm, and greater. Othersystems and methods for forming a dielectric film on a substrate asknown to those skilled in the art of both spin-on dielectric technologyand CVD dielectric technology are suitable for the invention.

The dielectric film can, for example, be characterized as a lowdielectric constant (or low-k) dielectric film. The dielectric film mayinclude at least one of an organic, inorganic, and inorganic-organichybrid material. Additionally, the dielectric film may be porous ornon-porous. For example, the dielectric film may include an inorganic,silicate-based material, such as oxidized organosilane (or organosiloxane), deposited using CVD techniques. Examples of such filmsinclude Black Diamond™ CVD organosilicate glass (OSG) films commerciallyavailable from Applied Materials, Inc., or Coral™ CVD films commerciallyavailable from Novellus Systems. Additionally, for example, porousdielectric films can include single-phase materials, such as a siliconoxide-based matrix having terminal organic side groups that inhibitcross-linking during a curing process to create small voids (or pores).Additionally, for example, porous dielectric films can includedual-phase materials, such as a silicon oxide-based matrix havinginclusions of organic material (e.g., a porogen) that is decomposed andevaporated during a curing process. Alternatively, the dielectric filmmay include an inorganic, silicate-based material, such as hydrogensilsesquioxane (HSQ) or methyl silsesquioxane (MSQ), deposited using SODtechniques. Examples of such films include FOx HSQ commerciallyavailable from Dow Corning, XLK porous HSQ commercially available fromDow Corning, and JSR LKD-5109 commercially available from JSRMicroelectronics. Still alternatively, the dielectric film can includean organic material deposited using SOD techniques. Examples of suchfilms include SiLK-I, SiLK-J, SiLK-H, SiLK-D, porous SiLK-T, porousSiLK-Y, and porous SiLK-Z semiconductor dielectric resins commerciallyavailable from Dow Chemical, and FLARE™, and Nano-glass commerciallyavailable from Honeywell.

Also, as illustrated in FIG. 1A, a transfer system 30 can be coupled tothe drying system 10 in order to transfer substrates into and out of thedrying system 10 and the curing system 20, and exchange substrates witha multi-element manufacturing system 40. Transfer system 30 may transfersubstrates to and from drying system 10 and curing system 20 whilemaintaining a vacuum environment. The drying and curing systems 10, 20,and the transfer system 30 can, for example, include a processingelement within the multi-element manufacturing system 40. For example,the multi-element manufacturing system 40 can permit the transfer ofsubstrates to and from processing elements including such devices asetch systems, deposition systems, coating systems, patterning systems,metrology systems, etc. In order to isolate the processes occurring inthe first and second systems, an isolation assembly 50 can be utilizedto couple each system. For instance, the isolation assembly 50 caninclude at least one of a thermal insulation assembly to provide thermalisolation, and a gate valve assembly to provide vacuum isolation. Thedrying and curing systems 10 and 20, and transfer system 30 can beplaced in any sequence.

Alternately, in another embodiment of the invention, FIG. 1B shows aprocessing system 100 for treating a dielectric film on a substrate. Theprocessing system 100 includes a “cluster-tool” arrangement for a dryingsystem 110, and a curing system 120. For example, the drying system 110can be configured to remove, or reduce to sufficient levels, one or morecontaminants in the dielectric film, including, for example, moisture,solvent, porogen, or any other contaminant that may interfere with acuring process performed in the curing system 120. Additionally, forexample, the curing system 120 can be configured to cure the dielectricfilm by causing or partially causing cross-linking within the dielectricfilm in order to, for example, improve the mechanical properties of thedielectric film. Furthermore, the processing system 100 can optionallyinclude a post-treatment system 140 configured to modify the cureddielectric film. For example, post-treatment can include spin coating orvapor depositing another film on the dielectric film in order to promoteadhesion for subsequent films or improve hydrophobicity. Alternatively,for example, adhesion promotion may be achieved in a post-treatmentsystem by lightly bombarding the dielectric film with ions.

Also, as illustrated in FIG. 1B, a transfer system 130 can be coupled tothe drying system 110 in order to transfer substrates into and out ofthe drying system 110, and can be coupled to the curing system 120 inorder to transfer substrates into and out of the curing system 120, andcan be coupled to the optional post-treatment system 140 in order totransfer substrates into and out of the post-treatment system 140.Transfer system 130 may transfer substrates to and from drying system110, curing system 120 and optional post-treatment system 140 whilemaintaining a vacuum environment.

Additionally, transfer system 130 can exchange substrates with one ormore substrate cassettes (not shown). Although only two or three processsystems are illustrated in FIG. 1B, other process systems can accesstransfer system 130 including for example such devices as etch systems,deposition systems, coating systems, patterning systems, metrologysystems, etc. In order to isolate the processes occurring in the dryingand curing systems, an isolation assembly 150 can be utilized to coupleeach system. For instance, the isolation assembly 150 can include atleast one of a thermal insulation assembly to provide thermal isolation,and a gate valve assembly to provide vacuum isolation. Additionally, forexample, the transfer system 130 can serve as part of the isolationassembly 150.

Alternately, in another embodiment of the invention, FIG. 1C shows aprocessing system 200 for treating a dielectric film on a substrate. Theprocessing system 200 includes a drying system 210, and a curing system220. For example, the drying system 210 can be configured to remove, orreduce to sufficient levels, one or more contaminants in the dielectricfilm, including, for example, moisture, solvent, porogen, or any othercontaminant that may interfere with a curing process performed in thecuring system 220. Additionally, for example, the curing system 220 canbe configured to cure the dielectric film by causing or partiallycausing cross-linking within the dielectric film in order to, forexample, improve the mechanical properties of the dielectric film.Furthermore, the processing system 200 can optionally include apost-treatment system 240 configured to modify the cured dielectricfilm. For example, post-treatment can include spin coating or vapordepositing another film on the dielectric film in order to promoteadhesion for subsequent films or improve hydrophobicity. Alternatively,for example, adhesion promotion may be achieved in a post-treatmentsystem by lightly bombarding the dielectric film with ions.

Drying system 210, curing system 220, and post-treatment system 240 canbe arranged horizontally or may be arranged vertically (i.e., stacked).Also, as illustrated in FIG. 1C, a transfer system 230 can be coupled tothe drying system 210 in order to transfer substrates into and out ofthe drying system 210, can be coupled to the curing system 220 in orderto transfer substrates into and out of the curing system 220, and can becoupled to the optional post-treatment system 240 in order to transfersubstrates into and out of the post-treatment system 240. Transfersystem 230 may transfer substrates to and from drying system 210, curingsystem 220 and optional post-treatment system 240 while maintaining avacuum environment.

Additionally, transfer system 230 can exchange substrates with one ormore substrate cassettes (not shown). Although only three processsystems are illustrated in FIG. 1C, other process systems can accesstransfer system 230 including for example such devices as etch systems,deposition systems, coating systems, patterning systems, metrologysystems, etc. In order to isolate the processes occurring in the firstand second systems, an isolation assembly 250 can be utilized to coupleeach system. For instance, the isolation assembly 250 can include atleast one of a thermal insulation assembly to provide thermal isolation,and a gate valve assembly to provide vacuum isolation. Additionally, forexample, the transfer system 230 can serve as part of the isolationassembly 250.

At least one of the drying system 10 and the curing system 20 of theprocessing system 1 as depicted in FIG. 1A includes at least twotransfer openings to permit the passage of the substrate therethrough.For example, as depicted in FIG. 1A, the drying system 10 includes twotransfer openings, the first transfer opening permits the passage of thesubstrate between the drying system 10 and the transfer system 30 andthe second transfer opening permits the passage of the substrate betweenthe drying system and the curing system. However, regarding theprocessing system 100 depicted in FIG. 1B and the processing system 200depicted in FIG. 1C, each treatment system 110, 120, 140 and 210, 220,240, respectively, includes at least one transfer opening to permit thepassage of the substrate therethrough.

Referring now to FIG. 2, a drying system 300 is shown according toanother embodiment of the invention. Drying system 300 includes a dryingchamber 310 configured to produce a clean, contaminant-free environmentfor drying a substrate 325 resting on substrate holder 320. The dryingsystem 300 can include a thermal treatment device 330 coupled to dryingchamber 310, or to substrate holder 320, and configured to evaporatecontaminants, such as for example moisture, residual solvent, etc., byelevating the temperature of substrate 325. Furthermore, the dryingsystem 300 can include a microwave treatment device 340 coupled to thedrying chamber 310, and configured to locally heat contaminants in thepresence of an oscillating electric field. The drying process canutilize the thermal treatment device 330, or the microwave treatmentdevice 340, or both to facilitate drying a dielectric film on substrate325.

The thermal treatment device 330 can include one or more conductiveheating elements embedded in substrate holder 320 coupled to a powersource and a temperature controller. For example, each heating elementcan include a resistive heating element coupled to a power sourceconfigured to supply electrical power. Alternatively, the thermaltreatment device 330 can include one or more radiative heating elementscoupled to a power source and a controller. For example, each radiativeheating element can include a heat lamp coupled to a power sourceconfigured to supply electrical power. The temperature of substrate 325can, for example, range from approximately 20° C. to approximately 500°C., and desirably, the temperature may range from approximately 200° C.to approximately 400° C.

The microwave treatment source 340 can include a variable frequencymicrowave source configured to sweep the microwave frequency through abandwidth of frequencies. Frequency variation avoids charge build-upand, hence, permits damage-free application of microwave dryingtechniques to sensitive electronic devices.

In one example, the drying system 300 can include a drying systemincorporating both a variable frequency microwave device and a thermaltreatment device, such as for example the microwave furnace commerciallyavailable from Lambda Technologies, Inc. (860 Aviation Parkway, Suite900, Morrisville, N.C. 27560). For additional details, a microwavefurnace is described in U.S. Pat. No. 5,738,915, assigned to LambdaTechnologies, Inc., and entitled “Curing polymer layers on semiconductorsubstrates using variable frequency microwave energy”; the entirecontents of which are incorporated herein by reference.

The substrate holder 320 may or may not be configured to clamp substrate325. For instance, substrate holder 320 may be configured tomechanically or electrically clamp substrate 325.

Referring again to FIG. 2, drying system 300 can further include a gasinjection system 350 coupled to the drying chamber and configured tointroduce a purge gas to drying chamber 310. The purge gas can, forexample, include an inert gas, such as a noble gas or nitrogen.Additionally, drying system 300 can include a vacuum pumping system 355coupled to drying chamber 310 and configured to evacuate the dryingchamber 310. During a drying process, substrate 325 can be subject to aninert gas environment with or without vacuum conditions.

Furthermore, drying system 300 can include a controller 360 coupled todrying chamber 310, substrate holder 320, thermal treatment device 330,microwave treatment device 340, gas injection system 350, and vacuumpumping system 355. Controller 360 includes a microprocessor, a memory,and a digital I/O port capable of generating control voltages sufficientto communicate and activate inputs to the drying system 300 as well asmonitor outputs from the drying system 300. A program stored in thememory is utilized to interact with the drying system 300 according to astored process recipe. The controller 360 can be used to configure anynumber of processing elements (310, 320, 330, 340, 350, or 355), and thecontroller 360 can collect, provide, process, store, and display datafrom processing elements. The controller 360 can include a number ofapplications for controlling one or more of the processing elements. Forexample, controller 360 can include a graphic user interface (GUI)component (not shown) that can provide interfaces that enable a user tomonitor and/or control one or more processing elements.

Referring now to FIG. 3, a curing system 400 is shown according toanother embodiment of the present invention. Curing system 400 includesa curing chamber 410 configured to produce a clean, contaminant-freeenvironment for curing a substrate 425 resting on substrate holder 420.Curing system 400 further includes two or more radiation sourcesconfigured to expose substrate 425 having the dielectric film toelectro-magnetic (EM) radiation at multiple EM wavelengths. The two ormore radiation sources can include an infrared (IR) radiation source 440and an ultraviolet (UV) radiation source 445. The exposure of thesubstrate to UV radiation and IR radiation can be performedsimultaneously, sequentially, or over-lapping one another.

The IR radiation source 440 may include a broad-band IR source, or mayinclude a narrow-band IR source. The IR radiation source can include oneor more IR lamps, or one or more IR lasers (continuous wave (CW),tunable, or pulsed), or any combination thereof. The IR power can rangefrom approximately 0.1 mW to approximately 2000 W. The IR radiationwavelength can range from approximately 1 micron to approximately 25microns and, desirably, can range from approximately 8 microns toapproximately 14 microns. For example, the IR radiation source 440 caninclude an IR element, such as a ceramic element or silicon carbideelement, having a spectral output ranging from approximately 1 micron toapproximately 25 microns, or the IR radiation source 440 can include asemiconductor laser (diode), or ion, Ti:sapphire, or dye laser withoptical parametric amplification.

The UV radiation source 445 may include a broad-band UV source, or mayinclude a narrow-band UV source. The UV radiation source can include oneor more UV lamps, or one or more UV lasers (continuous wave (CW),tunable, or pulsed), or any combination thereof. UV radiation can begenerated, for instance, from a microwave source, an arc discharge, adielectric barrier discharge, or electron impact generation. The UVpower density can range from approximately 0.1 mW/cm² to approximately2000 mW/cm². The UV wavelength can range from approximately 100nanometers (nm) to approximately 600 nm and, desirably, can range fromapproximately 200 nm to approximately 400 nm. For example, the UVradiation source 445 can include a direct current (DC) or pulsed lamp,such as a Deuterium (D₂) lamp, having a spectral output ranging fromapproximately 180 nm to approximately 500 nm, or the UV radiation source445 can include a semiconductor laser (diode), (nitrogen) gas laser,frequency-tripled Nd:YAG laser, or copper vapor laser.

The IR radiation source 440, or the UV radiation source 445, or both,may include any number of optical device to adjust one or moreproperties of the output radiation. For example, each source may furtherinclude optical filters, optical lenses, beam expanders, beamcollimators, etc. Such optical manipulation devices as known to thoseskilled in the art of optics and EM wave propagation are suitable forthe invention.

The substrate holder 420 can further include a temperature controlsystem that can be configured to elevate and/or control the temperatureof substrate 425. The temperature control system can be a part of athermal treatment device 430. The substrate holder 420 can include oneor more conductive heating elements embedded in substrate holder 420coupled to a power source and a temperature controller. For example,each heating element can include a resistive heating element coupled toa power source configured to supply electrical power. The substrateholder 420 could optionally include one or more radiative heatingelements. The temperature of substrate 425 can, for example, range fromapproximately 20° C. to approximately 500° C., and desirably, thetemperature may range from approximately 200° C. to approximately 400°C.

Additionally, the substrate holder 420 may or may not be configured toclamp substrate 425. For instance, substrate holder 420 may beconfigured to mechanically or electrically clamp substrate 425.

Referring again to FIG. 3, curing system 400 can further include a gasinjection system 450 coupled to the curing chamber 410 and configured tointroduce a purge gas to curing chamber 410. The purge gas can, forexample, include an inert gas, such as a noble gas or nitrogen.Alternatively, the purge gas can include other gases, such as forexample H₂, NH₃, C_(x)H_(y), or any combination thereof. Additionally,curing system 400 can further include a vacuum pumping system 455coupled to curing chamber 410 and configured to evacuate the curingchamber 410. During a curing process, substrate 425 can be subject to apurge gas environment with or without vacuum conditions.

Furthermore, curing system 400 can include a controller 460 coupled todrying chamber 410, substrate holder 420, thermal treatment device 430,IR radiation source 440, UV radiation source 445, gas injection system450, and vacuum pumping system 455. Controller 460 includes amicroprocessor, a memory, and a digital I/O port capable of generatingcontrol voltages sufficient to communicate and activate inputs to thecuring system 400 as well as monitor outputs from the curing system 400.A program stored in the memory is utilized to interact with the curingsystem 400 according to a stored process recipe. The controller 460 canbe used to configure any number of processing elements (410, 420, 430,440, 445, 450, or 455), and the controller 460 can collect, provide,process, store, and display data from processing elements. Thecontroller 460 can include a number of applications for controlling oneor more of the processing elements. For example, controller 460 caninclude a graphic user interface (GUI) component (not shown) that canprovide easy to use interfaces that enable a user to monitor and/orcontrol one or more processing elements.

The controllers 360 and 460 may be implemented as a DELL PRECISIONWORKSTATION 610™. The controllers 360 and 460 may also be implemented asa general purpose computer, processor, digital signal processor, etc.,which causes a substrate processing apparatus to perform a portion orall of the processing steps of the invention in response to thecontrollers 360 and 460 executing one or more sequences of one or moreinstructions contained in a computer readable medium. The computerreadable medium or memory for holding instructions programmed accordingto the teachings of the invention and for containing data structures,tables, records, or other data described herein. Examples of computerreadable media are compact discs, hard disks, floppy disks, tape,magneto-optical disks, PROMs (EPROM, EEPROM, flash EPROM), DRAM, SRAM,SDRAM, or any other magnetic medium, compact discs (e.g., CD-ROM), orany other optical medium, punch cards, paper tape, or other physicalmedium with patterns of holes, a carrier wave (described below), or anyother medium from which a computer can read.

The controllers 360 and 460 may be locally located relative to thedrying system 300 and curing system 400, or may be remotely locatedrelative to the drying system 300 and curing system 400 via an internetor intranet. Thus, the controllers 360 and 460 can exchange data withthe drying system 300 and curing system 400 using at least one of adirect connection, an intranet, and the internet. The controllers 360and 460 may be coupled to an intranet at a customer site (i.e., a devicemaker, etc.), or coupled to an intranet at a vendor site (i.e., anequipment manufacturer). Furthermore, another computer (i.e.,controller, server, etc.) can access controllers 360 and 460 to exchangedata via at least one of a direct connection, an intranet, and theinternet.

Referring now to FIG. 4, a method of treating a dielectric film on asubstrate is described according to another embodiment. The methodincludes a flow chart 500 beginning in 510 with drying the dielectricfilm on the substrate in a first processing system. The first processingsystem includes a drying system configured to remove, or partiallyremove, one or more contaminants in the dielectric film, including, forexample, moisture, solvent, porogen, or any other contaminant that mayinterfere with a subsequent curing process.

In 520, the dielectric film is cured in a second processing system. Thesecond processing system includes a curing system configured to cure thedielectric film by causing or partially causing cross-linking within thedielectric film in order to, for example, improve the mechanicalproperties of the dielectric film. Following the drying process, thesubstrate can be transferred from the first process system to the secondprocessing system under vacuum in order to minimize contamination.Therein, the substrate is exposed to UV radiation and IR radiation.Additionally, following the drying and curing processes, the dielectricfilm may optionally be post-treated in a post-treatment systemconfigured to modify the cured dielectric film. For example,post-treatment can include spin coating or vapor depositing another filmon the dielectric film in order to promote adhesion for subsequent filmsor improve hydrophobicity. Alternatively, for example, adhesionpromotion may be achieved in a post-treatment system by lightlybombarding the dielectric film with ions. One such post-treatment thatcan be suitable for the present invention is described in U.S. Pat. No.5,714,437, entitled Method of improving adhesion between thin films, theentire contents of which are incorporated herein by reference.

Although only certain exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention.

The invention claimed is:
 1. A method of curing a low-k dielectric film,comprising: disposing a substrate, having said low-k dielectric filmthereon, on a substrate holder in a curing system, the substrate holderhaving a heating element therein; heating the substrate by controllingsaid heating element; exposing said low-k dielectric film to infrared(IR) radiation to facilitate a first curing mechanism within thedielectric film; exposing said low-k dielectric film to ultraviolet (UV)radiation to facilitate a second curing mechanism that is different fromthe first curing mechanism within the low-k dielectric film; and curingsaid low-k dielectric film by varying delivery of said IR radiation andsaid UV radiation to the low-k dielectric film to facilitate said firstand second curing mechanism at different stages of curing such thatmechanical properties of the low-k dielectric film are improved whilemaintaining a dielectric constant of the low-k film less than adielectric constant of silicon dioxide.
 2. the method of claim 1,wherein said first and second curing mechanisms are selected from agroup consisting of generation of cross-link initiators, burn-out ofporogens, decomposition of porogens and film cross-linking.
 3. Themethod of claim 2, wherein said first curing mechanism is selected froma group consisting of generation of cross-link initiators and porogenburn-out.
 4. The method of claim 3, wherein said first curing mechanismis generation of cross-link initiators, and said second curing mechanismis film cross-linking.
 5. The method of claim 1, wherein said curingcomprises improving at least one of a Young's modulus, film harness, andfracture toughness of said low-k film.
 6. The method of claim 5, whereinsaid curing comprises maintaining a dielectric constant property of thelow-k film at less than 3.0.
 7. The method of claim 6, wherein saidcuring comprises maintaining a dielectric constant property of the low-kfilm at less 2.5.
 8. The method of claim 6, wherein said curingcomprises maintaining a dielectric constant property of the low-k filmat a value ranging from 1.6 to 2.7.
 9. The method of claim 7, whereinsaid curing comprises maintaining a dielectric constant property of thelow-k film at about 1.6.
 10. The method of claim 1, wherein saiddisposing comprises disposing a substrate, having a porous low-kdielectric film thereon, in a curing system.
 11. The method of claim 10,wherein said disposing comprises disposing a substrate, having a siliconoxide based matrix including an organic material porogen.
 12. The methodof claim 1, wherein said exposing said dielectric film to IR radiationcomprises exposing said dielectric film to said IR radiation at anenergy level which corresponds to a main absorption peak of thedielectric film.
 13. The method of claim 12, wherein: said disposingcomprises disposing a substrate having siloxane-based organosilicatecontaining dielectric film thereon, in a curing system, and saidexposing said low-k dielectric film to infrared (IR) radiation comprisesexposing said low-k dielectric film to infrared (IR) radiation ofapproximately 9 microns.
 14. The method of claim 1, wherein said curingcomprises simultaneously exposing said dielectric film to said IRradiation and to said UV radiation.
 15. The method of claim 1, whereinsaid curing comprises sequentially exposing said dielectric film to saidIR radiation and to said UV radiation.
 16. The method of claim 15,wherein said sequentially exposing comprises exposing said dielectricfilm to IR radiation at least one of before and after said exposing saiddielectric film to UV radiation.
 17. The method of claim 1, wherein saidexposing said dielectric film to UV radiation comprises a UV wavelengthranging from about 100 nm to about 600 nm.
 18. The method of claim 17,wherein said exposing said dielectric film to UV radiation comprises aUV wavelength ranging from about 200 nm to about 400 nm.
 19. The methodof claim 1, wherein said exposing said dielectric film to IR radiationcomprises an IR wavelength ranging from 1 to 25 μm.
 20. The method ofclaim 1, further comprising controlling a temperature of said substrateto be approximately 500° C. or less using said heating element.